Tunnel structure

ABSTRACT

Disclosed herein is a new and improved tunnel structure or the like for a tunnel being driven in a predetermined direction through an excavation having a workface. The new tunnel structure includes a lining of concrete installed in sections; a front formwork assembly closing off the lining toward the workface; the formwork comprising end overlapping, self-supporting, panelshaped structural elements being provided with pockets which are in spaced relation, are alternatively pressed out toward opposing sides, are successively arranged, in the concrete forming the lining, in rectilinear rows extending transversely to the direction of driving and through which pockets the rod-like connecting members are passed; the rod-like members are passed through the pockets in the area of overlap of the structural elements; the concrete for the lining sections initially being introduced and vibrated behind the panel-shaped, self-supporting structural elements serving as a permanent formwork; and in each section of lining of the tunnel structure, the end of the structural elements which are forwardmost in the direction of driving are maintained free of concrete for connection, by means of the rod-like connecting means, with the rear ends of the nextto-be installed structural elements of the next section of the lining to be installed.

ernold Dec. 24, 1974 TUNNEL STRUCTURE [75] Inventor: Jean P. Bernold,Walenstadt,

, Switzerland [73] Assignee: Hans Walter Pfeiffer, a part interest 22Filed: Mar. 15,1973

' 211 Appl. No.: 341,600

Related U.S. Application Data [62] Division of Ser. No. 170,770, Aug.ll, 1971, Pat. No. 3,751,929, which iS a division of Ser. No. 798,747,Feb. 12, 1969, Pat. No. 3,60l,945.

Primary Examiner-Dennis L. Taylor ,Attorney, Agent, or FirmMandeville &Schweitzer 57 1 ABSTRACT Disclosed herein is a new andimproved tunnelstructure or the like for a tunnel being driven in a predetermineddirection through an excavation having a workface. The newtunnelstructure includes a lining of concrete installed in sections; afront formwork assembly closing off the lining toward the workface; theformwork comprising end overlapping, selfsupporting, panel shapedstructural elements being provided with pockets which are in spacedrelation, are alternatively pressed out toward opposing sides, aresuccessively arranged, in the concrete forming the lining, inrectilinear rows extending transversely to the direction of driving andthrough which pockets the rod-like connecting members are passed; therod-like members are passed through the pockets in the area of overlapof the structural elements; the concrete for the lining sectionsinitially being introduced and vibrated behind the panel-shaped,self-supporting structural elements serving as a permanent formwork; andin each section of lining of the tunnel structure, the end of thestructural elements which are forwardmost in the direction of drivingare maintained free of concrete for connection, by means of the rod-likeconnecting means, with the rear ends of the next-to-be installedstructural elements of the next section of the lining to be installed.

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PAIENIEnuzczmam SHEEI IBM 13 TUNNEL STRUCTURE RELATION TO COPENDINGAPPLICATIONS This application is a division of application Ser. No.170,770, filed Aug. 11, 1971, now US. Pat. No. 3,751,929, which, in turnwas a division of application Ser. No. 798,747, filed Feb. 12, 1969 nowUS. Pat. No. 3,601,945. The drawings and specification herein areidentical with those on file in copending and related application Ser.No. 262,216 now abandoned.

According to the present invention, there is provided a panel-likestructural unit particularly for use as permanent formwork andreinforcement in concrete constructions, said unit being formed withcorrugations, at least one creast of which is depressed at intervals toform a row of pockets for receiving a connecting element extendinglongitudinally of the corrugations,

' whereby overlapping units are connectable, the pockets each decreasingin width, considered longitudinally of the corrugations, with increasein depth of the units mate readily both when the units are flat, and

when they are deformed to construct an arch during tunnel construction.

Inter-engagement of the units in the overlap zone is additionallyfacilitated by the fact that the pockets are arched to reduce theirwidth, for example being of U or V-fo rm cross-section.

' According to another advantageous aspect of the invention, the edgesdefining the pockets merge substan tially along a straight line with thetroughs adjacent the crest or crests in which the pockets are formed.This simplifies manufacture of the unit because it is possible to use atool simpler than that used for conventional units. At the same time,flexural strength is increased, thus enabling the units to be installedwith greater unsupported lengths.

A particularly favourable cross-sectional form for the corrugationsis'obtaine'd where the sides of the troughs include between them anangle of about 90, because in this way the corrugations lie tightlyadjacent one another in the overlap zone and offer particularly highresistance to'pressure and tension.

. The panel-like structural unit according to the present invention isused to line tunnels and galleries. In this case, the unit acts aspermanent formwork which is back-filled with concrete and optionallycovered with a sealing compound on that side facing the tunnel.

In concrete construction, it is common practice to use permanentformwork consisting essentially of a framework of supporting elementsand rods, wire netting or full-length panels secured between them.

However, tunnels and galleries have to be lined under circumstancesdiffering from those encountered in normal concrete construction, suchas the ground pressure whose effect is largely governed by the nature ofthe surrounding rock, and for which appropriate allowance has to bemade. I I

This aspect of the invention is based on the recognition that idealprogress in tunnel driving can only be made when the concrete vault isinstalled simultaneously with the advance in the tunnel profile. In anymountain, except in quicksand where the water pressure is a criticalfactor, a subterranean cavity or hollow can remain open for a certainperiod of time without any need for support, i.e., without any signs ofdetectable ground pressure occurring and putting strain upon any lininginstalled. The relaxation zones around the cavity are gradually formedand over a period of time are propagated further and further into therock because the pressure takes some time to develop because as a rulethe mountain only undergoes plastic deformation some time afterrelaxation has been absorbed by the lining.

Accordingly, it is a further object of the invention to provide aprocess by means of which a concrete lining of the requisite thicknesscan be erected in this relatively short period of time before groundpressure is applied, in order thus to facilitate considerably faster andmore economic tunnel driving.

According to a feature of the invention, this object is achieved byinstalling erection arches whose external outline correspondssubstantially to the internal crosssection of the lined tunnel orgallery to be constructed, right up to the working face after blastingand removal of the debris, sealing off the cavity to be concreted at itsfront end by frontal formwork, and placing the panel-like units providedby this invention on the erection arches in alignment with thepreviously installed units, and back-filling the space between the unitsand the tunnel with concrete, which is preferably vibrated, up to thetunnel apex. In this way, it is possible to produce a lining which isstrong enough to withstand the ground pressure as soon as it begins tooccur so that extremely fast progress can be made. Experience has shownthat ground pressure actually begins to exert its effect when thefreshly installed concrete lining is completed and has acquired therequisite bearing strengthThe minimum period which can be expected inany rock and within which the lining has to be installed, is beatenwithout any difficulty during installation of the lining.

By virtue of the process according to the invention, it is possible toproduce a concrete lining adapted to the tunnel and which, having beenvibrated, lies tight against the workface and prevents furtherdisintegration of the rock through foreign influences such as air andwater in particular. The lining which is loadbearing immediately it hasbeen installed distributes the pressure of the weaker rock to strongerlayers of rock and thus eliminates the danger zone directly behind theworkface. At the same time, the units supported by the erection arcs andsimultaneously acting as formwork and reinforcement, prevent theconcrete jacket from cracking under the effect of blasting so that onedisadvantage affecting making safe with pneumatically applied concreteis eliminated.

The process according to the invention thus enables a concretesupporting structure to be erected in a single operation on theconstruction site itself, the ground pressures occurring being absorbedby a homogeneous structure of rock-concrete formwork and reinforcementof the erection arches without affecting progress in any way. Inaddition, the panel-like structural units acting as formwork andreinforcement may be designed in such a way as to produce a firm bondbetween the concrete and a sealing compound sprayed on to that surfacefacing the tunnel.

In the event of tunneling in swelling ground, a temporary, movablesheet-like support, consisting of elongated, plate-like lances two tothree times longer than the interval between the arches, is withadvantage used to make safe the roadway lying exposed between theworkface and the lining. The lances are provided along theirlongitudinal sides with interengaging guides which permit bending arounda longitudinal axis and limited deviation from the longitudinaldirection between tw adjacent lances.

A particularly favourable and practical design for the mutually guidinglances is obtained by arranging on one longitudinal edge of the lance aguide channel open at both ends which is accessible from the edgethrough a longitudinal slot, and on the other longitudinal edge a slidemember of T-form cross-section which engages with clearance in theadjacent guide channel. Toothlike ribs with which a device for movingthe lance forwards may be releasably engaged, may be provided on thatside of the lance facing the tunnel. To prevent the lances, parts ofwhich are permanently situated in the concrete, from bonding with theconcrete, they are preferably made from steel, being ground smooth onthe outside. The lances are also fitted with a point which tapersconically at that end facing the tunnel.

The device for moving the lances forwards may consist of a pneumaticcylinder which, on the extendable rod of the piston, has a claw forengaging in the toothlike ribs on the lances, and whose cylinder isarranged to be supported by the side face of an erection arch.

The panel-like units may also be used for performing another functionfrequently required in building construction, namely to make safeexposed ground and rock. It has been found that this function can beperformed in a unique advantageous manner by arranging the permanentformwork in front of and at a distance from the area to made safe andfilling the space behind the formwork 'with concrete introduced throughthe formwork. It is particularly easy with an arrangement such as thisto introduce the concrete by spraying it through at a right-angle to thestructural unit.

To strengthen a trench, the permanent formwork is secured to drivenvertical pilot beams, backfilled and extended downwards in sections asexcavation continues.

It is necessary to strengthen a tunnel surface and if it is intended toprotect the formwork against corrosion, the the spray-through processreferred to above may be applied, or alternatively a cement mortarcontaining a waterglass additive is initially sprayed on to that surfaceof the permanent formwork facing the tunnel, after which the space leftbetween formwork and tunnel wall is filled with concrete.

The invention is described in detail by way of example only in thefollowing with reference to the accompanying drawings, wherein:

FIG. I is a front elevation of two structural units overlapping at thepoint at which they are joined.

FIG. 2 is a partial section through the units shown in FIG. 1 on theline Il.

FIG. 3 is a front elevation of a modified embodiment of the structuralunit.

FIG. 4 is a section through FIG. 3 on the line III-III.

FIG. 5 is a front elevation corresponding to FIG. 1 of a structural unitinstalled in an arched position. the arching running parallel to therows of pockets.

FIG. 6 is a section through the unit shown in FIG. 1 which is archedabout an axis extending transversely of the rows of pockets.

FIG. 7 is a partial section through a completed tunnel or gallerylining.

FIG. 8 is a longitudinal section through a joint between two overlappingstructural units.

FIG. 9 is a plan view of the joint shown in FIG. 8.

FIG. 10 is a longitudinal section through a tunnel in the course ofconstruction.

FIG. 11 shows a tunnel lining partly in section and partly as a frontelevation.

FIG. 12 is a section through FIG. 11 on the line XII- XII.

FIG. 13 is a section corresponding to FIG. 12 through a frontal formworkclosing a concreting section.

FIG. 14 shows the arrangement illustrated in FIG. 13 after the formworkhas been backfilled with gravel.

FIG. 15 illustrates another possibility of producing frontal formwork.

FIg. 16 is a partial elevation of an erection arch of the kind used toline a tunnel.

FIG. 17 is a longitudinal section through a tunnel in the course ofbeing lined, lances being used to support the swelling rock.

FIG. 18 illustrates a tunnel lining of the kind shown in FIG. 17partlyin section and partly in side elevation.

FIG. 19 is a section through FIG. 18 on the line XVIII--XVIII.

FIG. 20 is a sectional view corresponding to FIG. 19 of anotherembodiment for frontal formwork in cases where lances are used.

FIG. 21 is a section through adjacent lances.

FIG. 22 is a plan view of a lance.

FIG. 23 is a side elevation of a lance.

FIG. 24 is a vertical partial section through a tunnel whose verticalwall consisting of soil has been made safe by the process according tothe invention.

FIG. 25 is a plan view of FIG. 24.

FIG. 26 is a partial elevation of a a structural unit provided with aninjection socket.

FIG. 27 is a section through FIG. 26 on the line XXVIXXVI.

FIG. 1 is a front elevation of two partly overlapping panel-likestructural units 1, 2 in which curved pockets are arranged in rows,radiating alternately from a central plane, E, E. The upwardly curvedpockets in the unit towards the bottom of the drawing are denoted by thereference 2a, whilst the downwardly directed pockets are denoted by thereference 2b. Similarly, the upper unit is provided with upwardlydirected pockets 2c and downwardly directed pockets 2d. As shown in theFigure, the pockets 2a and 2b and the pockets 2c and 2d lying one behindthe other form full-length openings A which even when two units areplaced one on top of the other, as shown in the Figure, leave free anopening A for accommodating a rod-like connect ing element. The pockets2a and 2b and the pockets 2c and 2d each begin flat on the centre planeE and E and, as shown in FIG. 2, form troughs which are concave fromtheoutsides and which are most pronounced at the tops of the pockets.

Arranged between each of the rows of pockets 2a, 2b and 2c. 2d is afull-length corrugation 3, 3a which forms a recess directed to only oneside of the unit, in the drawing downwards from the centre plane, E, E.and

ets 2a, 2b and 2c, 2d extending fruthest outwards, i.e.,

through the region in which the concave arching of the pockets is at itsmost pronounced. Through the arching of the pockets, the pockets whichlie one behind the other form openings which lie one behind the othersubstantially in the centre plane of the unit and each of which taperinwards funnel-like from the side edge of the pocket. As shown in FIG.2, those edges 40f the pockets which define its end faces include withthe planes E. E an angle 5 of less than 90. As-a result, the pockets arewedge-like in shape as seen from the side. The gaps between twosuccessive pockets are similarly wedge-shaped. This makes it easier tofit the pockets into one another in the overlap zone, whilst thestructural units lying one above the other assume relative to oneanother exactly the position shown in FIG. -2 in which a connectingelement can be inserted into the opening A lying one behind the other.The opening A also remains intact for the insertion of a thinnerconnecting element of somewhat smaller internal crosssection in caseswhere structural units arched around an axis extending transversely ofthe corrugations are overlapped.

ln thepanel-like unit lashown in FIGS. 3 and 4, which is suitableforexample for larger dimensions, the downwardly directed pockets 2fproject beyond the apex of the'corrugations 3. Those portions projectingfurthest outwards, both of the upwardly directed pockets 2e and of thedownwardly directed pockets 2f, form flat- V-shaped flutes 6,which,compared with FIG. 4,

whose apex is substantially level with that portion of again produce asubstantially funnel-like cross-sectonal form in the longitudinalopenings A surrounded by the pockets. l L

The panel-like structural units shown in FIGS. 1 to 4 can be installednot only flat but also, as shown in FIGS.

5 and 6, arched, for example for lining tunnels. For this I purpose, astructural unit 1 may be arched around an axis parallel to the directionof the rows of pockets, as shown in FIG. 5, or around an axis extendingtrans-- versely of the rows of pockets as shown in FIG. 6. The

corrugations provided between the rows of pockets allow bending in boththe aforementioned directions.

FIG. 7 is a section through a tunnel lined with the structural unitaccording tothe invention. For this purpose, unitsare initially joinedtogetherin an arrangement substantially corresponding to the requiredinternal'cross-section of the tunnel. The generally irregular gap leftbetween the rock and the unit 1 is filled with pneumatically applied orlean-mixed concrete 7. At the into those spaces which, on the tunnelside, extend up to the backs of the pockets 2a. At the same time, apermanent, reliable bond can be obtained on those surfaces 8a on whichthe material 8 comes into contact with the concrete 7 The same effect isobtained even when the surface facing the tunnel is'spr'ayed withconcrete rather than with the material 8, or otherwise coated. Inaddition, the special design of the structural unit in any caseguarantees an absolutely firm bond between the initially free-flowingcoating material and the unit 1. I

FIG. 8 is a section through a joint between two overlapping structuralunits. As already explained with reference to FIG. 1, the pockets 2a, 2band 2c, 2d lie on one another and fit in one another. In this way, andthrough engagement of the corrugation 3a of the upper unit with thecorrugation 3 of the unit beneath it, the two units are held preciselyin their positions relative to one another. The two elements areprevented from being separated from one anotherby means of a mandrelorrod-like connecting element 9 which acts as a lock and which at' one endis bent around substantially at a right-angle. To enable the connectingelement 9 to be inserted into the longitudinal opening, two pockets 2band 2d have been hollowed out in the embodiment shown in the proximityof the joint between the two structural units. In this way, free zonesare formed at the points denoted by the reference 10 from which theconnecting element 9 can be introduced.

The same circumstances arise out of FIG. 9 which is a plan view of ajoint.

When used as illustrated in FIG. 7, the concave depressions or troughswhich, as mentioned earlier on, are arranged at and are at their mostpronounced'at the tops of thepockets 2a-f, have the advantage that thesurface facing the tunnel is uneven and promotes particularly firmadhesion of the sealing material. To ensure that the material 8 adheresfirmly, bridges have to be formed between the areas in which thematerial 8 penetrates into the gaps between the outwardly directedpockets. In the case of pockets which are arched outwards at theirapices, the so-called bridge is thinnest at its centreQWith pocketsshowing the aforementioned design, a considerably larger proportion ofthe composition used for sealing rebounds when it is sprayed on so thatlosses are inevitable and considerable expense involved in applying thecomposition;

Through the inwardly directed arching of the pockets at their apices, itis also possible to avoid cavities in the concrete which areparticularly undesirable in the proximity of the sealing layer becausethey detrimentally affect the firm bond with this layer.

The process for lining tunnels and galleries is described in detail inthe following.

In FIG. 10, the tunnel or gallery in the courseof construction isdenoted by the reference 1 l. The front end of the advance, known as theworkface, from which another round is completed with the next drillingand blasting operation, is shown at 12. Erection arches 13 are erectedat suitable intervals apart in the tunnel, extending into the immediateproximity of the workface 12. The external outline 13 of the erectionarches 13 corresponds substantially to the internal cross-section of thecompleted tunnel. The front erection arch 14 whose outer profilesubstantially corresponds to the excavation line of the tunnel, isprovided with frontal formwork 24 which will be described in detailfurther After the erection arches 13, 14 have been erected true toprofile, the panel-like structural units 1 are placed on the outsides ofthe arches. The units 1 form a permanent formwork which at the same timeacts as reinforcement for the completed concrete lining. In the sivelyprepared lining sections. In addition, a substantially dovetail-likerecess 24a is formed in the end face of the finished concreting 7, whosefunction is also to provide a firm link to the following new concretingsection. When the panellike structural units are installed in the mannerdescribed, a cavity 20 is formed between them and the rock adjoining thetunnel excavation line, being filled with concrete following theinstallation of the units 1 progressing in an upward direction. Theconcrete is consolidated by vibration. In order to fill the last cavityremaining, situated at the tunnel apex, concrete is forced through asocket 34 extending through the frontal formwork. For this purpose, ahose coming from a suitable concrete pump is attached to the socket 34.

As apparent from the foregoing, the lining extending into the immediateproximity of the workface forms a strong, reliable support for thetunnel, even when the concrete is still liquid, which is alreadyinstalled before the ground pressure begins to exert its influence.Installation does not interfere with theboring operations at theworkface 12. The arrangement consisting of erection arches, structuralunits and concrete backfilling is so strong that it is able to withstandexplosive blasts.

FIG. diagrammatically illustrates a lining produced by the processaccording to the invention. With normal friable rock, substantially thefollowing procedure is adopted in practice:

On completion of blasting and debris clearance, two erection arches areerected true to profile and provided with iron spacer sections (notshown in the drawing). The panel-like structural units are then arrangedpanel by panel in an upward direction'on both sides of these arches toform a ring, and at the same time backfilled with concrete which isconsolidated by vibration. The

frontal formwork 24 facilitates clean processing of the concrete.

When driving the first metre of a tunnel, a quicksetting binder may beadded to the concrete so that drilling and blasting may be continuedstraightaway. As soon as an adequate safety zone has been establishedinside the mountain, addition of the quick-setting binder may bestopped. The other erection arches are set at intervals of l to 2 metresapart, depending upon the ground pressure. Larger intervals between thearches are not recommended for economic reasons, because otherwisepanel-like structural units of considerable thickness would have to beused.

To drive a tunnel in normal rock, 21 erection arches for example may beused. In this way, it is possible to obtain a permanently supportedtunnel section metres long in which the lining withstands any vibrationduring blasting until the concrete jacket has set. After a tunnelsection of this kind has been completed, the erection arches aredismantled at the rear and reinstalled at the front.

If the rock allows, the lining may remain up to 10-12 metres behind theworkface and may be installed by a second working party. However, theerection arches must be installed up to a point immediately behind theworkface and must be keyed in such a way that lateral displacement underthe effect of the explosives is impossible. The erection arches, whichin the embodiment shown are of I-profile, are of such dimensions thatthey are able to absorb the stresses occurring without distortion, andcan be used and re-used. As soon as the erection arches towards the rearend of the lining have been removed, that surface of the panel-likeunits facing the tunnel should be coated with a sealing compound. Thesealing compound is normally applied by spraying.

If the tunnel is being driven in highly friable rock, it is advisable toprepare the concrete lining with the aid of two erection arches and therequisite connecting elements. The profile of the arches is chosen independence upon the thickness of the concrete supporting structure whichis in turn governed by the ground pressure.

On completion of blasting and debris clearance, the two erection archesare erected true to profile and anchored. They are erected asdescribed'above. Installation of the panel-like structural units andintroduction of the concrete are also carried out as described above.The interval between the arches may amount to between 0.6 and 2.0metres.

A quick-setting binder should be added to the concrete in cases wherethe concreting in sections is repeated at time intervals of less than 10hours.

After the second round, i.e., on completion of the blasting operationsand debris clearance, the rear arch is removed and reinstalled in frontof the other arch. The panel-like structural units are joined to thosealready concreted in after they have been placed on the outer flange ofthe previous arch. More concrete is then introduced. The sealingcompound should be applied at some distance from the workface, althoughit is also possible to apply the compound directly after the lean-mixedconcrete has been introduced.

If ground pressure allows, between 6 and 8 erection arches may be usedand the operation carried out substantially on the lines describedearlier on.

As a precautionary measure and for generally making safe, a layer ofgunite may be applied either over the entire or only the endangered partof the before the erection arches are set up. In special cases, roofbolts may also be fitted for safety before the erection arches are setup.

The lining according to the invention is shown in the right-hand part ofFIG. 11, the left-hand part of which is a section through the liningafter concreting. As shown in the Figure, the panel-like structuralunits 1 lie on the outer flange 13a of the erection arch 13 beforeconcreting. The pockets 2a, 2b arranged in rows extend transversely ofthe tunnel axis in the embodiment shown.

The space between the rock and the structural units 1 is filled withconcrete 7. The concrete penetrates into the gaps behind the pocketsdirected towards the tunhe]. When a sealing layer 8 is applied,preferably by spraying, tothe surface facing the tunnel, the sealingcompound bonds with the concrete by virtue of the fact that itpenetrates from the tunnel side into the spaces behind the pocketsdirected towards the rock.

FIG. 12 is a section through FIG. 11 on the line XII- XII showing howthe freshly installed unit 1 is joined to the unit 1 concreted in duringthe previous working stage. Concreting and hence tunnel drivingprogresses from right to left in FIG. 12. The units are laid one on topof the other in zone 21 with their adjoining edges so that the pocketsdirected to both sides from the centre plane of the elements engage inone another. In doing so, they leave free an opening in which aconnecting rod 9 holding the adjacent elements together is inserted. Thefront end of the last unit 1 to be concreted in must project beyond theend of the concrete 7 in order to be able to make the connection.

To prevent the concrete form flowing out frontwards from the spacebetween the units 1, 1' and the rock during concreting, a seal orclosure must be provided at the-front end of a concrete section. Anembodiment serving this purpose is shown in FIG. 13. Another structuralunit 1 is joined tothe last element 1 to be concreted in the mannerdescribed above, except that the overlap of the front unit 1' over therear unit 1 is made so large that the front unit with the overlappingportion a can be bent up to the rock adjoining the tunnel ex cavationline. To prevent the concrete subsequently introduced behind thepreceding unit 1 from pushing out the closure formed by the portion 15a,a holding wire 15b may be fastened between the portion 15a of the frontunit 1' and the unit 1 adjoining it in a direction opposite to that inwhich the tunnel is being driven.

- FIG. 14 illustrates an embodiment of the invention in which the units1 and 1' are backfilled with round gravel 23, grit, pervious or aeratedconcrete, rather than with concrete. This type of lining is used forthose parts of the tunnel at which water has to be removed. Thestructural units are installed in thesame way as described above. Anadequately thick water-tight layer 8, for example of gunite, is appliedon the tunnel side. Every 5 to 8 metres an expansion joint 'is providedwhich is preferably sealed with flexible jointing tape. The waterissuing from the rock flows through cavities present in the gravel 23and the like to the bottom .of the tunnel where suitable outlets areprovided to prevent accumulation and hence the build up of pressure. Ifthe water is to be displaced behind the structural units, cement may beinjected into the back filling 23.

Another method of sealing the cavity to be concreted at its front end,is shown in FIG. 15. The sealing means is in the form of an erectionarch which forms a frontal formwork. The frontal formwork consists of abox-like projection attached to that side facing the cavity to beconcreted which extends over the entire length of the arch.

The box forming the frontal formwork consists of a wedge-like projection24 which extends out from the outer' flange 13a of the arch l3 and whichis closed by a web 25 parallel to the inner flange 13b of the erectionarch. The web 25 is at a distance from the flange 13b wide enough toallow insertion of a structural unit 1. In this way, a cavity 26 isformed, accommodating the front end of the last element to be installed.This end remains free during concreting as shown in FIG. 15.

The wedge-like projection 24 of the frontal formwork leaves acorresponding recess in the end face of the completed concrete sectioninto which the concrete of the next concreting section penetrates sothat a substantially dovetail-like union is established between theconcrete initially introduced and the concrete subsequently introduced.When the concrete is sufficiently hard, arches removed from thecompleted tunnel section are reinstalled, in accordance with theprogress of the tunnel, so that the arch adjoining the front end of thenew concreting section again has frontal formwork and through its outerflange 13a closely follows the tunnel excavation line.

FIG. 16 illustrates a joint between two arch sections forming oneerection arch. Hinged flaps 28a and 28b are secured to the inner flanges13b of the arches. A bolt 27 which forms the hinge spindle is pushedthrough the coincident openings in the hinged flaps 18a and 18b andsuitably secured inposition.

Transverse flanges 29a and 2% are secured to the adjoining end faces ofthe arch sections between the outer flange 13a and the inner flange 13b.These transverse flanges have openings through which a set bolt 30extends. In the shank of the bolt there is a transverse opening whosefunction is to accommodate a wedge 31. By introducing the bolt 30 andknocking in the wedge 31, a first connection is established between thearch sections.

When the tunnel is driven in swelling rock, and the tunnels walls haveto be strengthened up to the workface, the procedure described in thefollowing with reference to FIGS. 17 to 23 may be adopted. As shown inFIG. 17, the front erection arches 13 are installed as guide arches forlances 32 moved hydraulically forwards which strengthen the walls of thetunnel. This means that the outer flange 13a is located at such adistance from the rock surrounding the excavation line that the lances32 lie tight against the rock. The web depth of the guide archescorresponds to the thickness of the lining to be installed.

After the arches have been installed true to profile and anchored, thelances 32 are introduced. As will explained further on, the lances forma jacket which sur rounds the tunnel. They are moved forwards by apneumatic cylinder 33 which, through its extendable piston rod 34,engages the lance to be pushed forward and at its opposite end issupported by a guide arch. The pump and the supply vessel for thepressure liquid for feeding the cylinder 33 is shown at 35.

FIG. 18 is anillustration corresponding substantially to FIG. 11. Asshown in the Figure, the panel-like units 1 are placed on the innerflange 13b while the lances 32 are supported by the outer flanges 13a.The cavity between the flanges ans the lining units is filled withconcrete 7 in the manner described above. Accordingly, the rear ends ofthe lances are situated in the concrete.

The arrangement shown in FIGS. 17 and 18 is again shown in FIG. 19 in asection on the line XVIII-XVIII of FIG. 18. The cavity to be concretedis in this case closed by blocks or boards 13c adapted to the shape ofthe arches, being arranged between the lances 32 and the units 1.

In cases where an arch corresponding to FIG. 15 with frontal formwork isused, the arrangement shown in FIG. 20 is obtained. The lances again lieon the outer flanges 13a of the arches 13, while the front end of theunit I, initially to be kept free from the concrete, engages in thecavity 26 of the frontal formwork 24, 25. When the lances are movedforwards, a cavity 7a in which concrete is injected is formed betweenthe concrete 7 and the rock.

As shown in FIG. 21, the lances 32 are in the form of panel-like orplate-like hollow bodies which are two to three times longer than theintervals between the arches 13. Situated on each narrow side there is aguide 37 open at both ends which is accessible from outside through alongitudinal slot 36 and in which a'slide 38 of substantially T-formcross-section attached to the adjacent lance engages. The guides 37 andthe slots 36 are made so large by comparison with the slides that thelances 32 can be adapted to the tunnel profile (cf. FIG. 18). A certainamount of lateral movement is guaranteed at the same time.

As shown in FIG. 22, the lances 32 are provided on that side facing thetunnel with tooth-like ribs 39 with which,-as shown in FIG. 20, thehydraulic cylinder 33 engages, being provided with corresponding claws41 at the end of its extendable piston rod 34. The cylinder 33 issupported by one of the arches 13, preferably that arch provided withfrontal formwork adjoining the last section to be concreted at its frontend. The cylinder 33 which as shown in FIG. 17 is provided with apressuremedium pump, is always attached to that lance 32 which is to bemoved forward. By virtue of the fact that the lances are individuallymoved forward, there is no need for an expensive hydraulic installation.Since the lances are never joined with the concrete, they are groundsmooth on the outside. Each lance 32 is provided with a point 40 whichis concave towards the tunnel side.

The particular lining section may be concreted after the point of thelance has been moved forward by approximately 1 metre. The panel-likestructural units are placed on the inner flange 13b of the arches andare assembled from the ground'towards the ridge. At the same time, theconcrete is introduced between the units and the lances and compacted byvibration. The frontal formwork ensures clean processing of theconcrete.

. In order to be able to inject concrete into the highest part of thecavity formed behind the units, a socket is preferably arranged on thearch provided with frontal formwork, to which a hose delivering theconcrete under pressure may be attached.

The strengthening of the tunnel section preceding the completed liningsection by the lances is extremely adaptable and may be carried out withminimum auxiliary forces. The use of the new panel-like structuralelement for making safe exposed ground and rock and the process appliedto this end is described in the following with reference to FIGS. 24 to27.

Hitherto, it has been common practice to safeguard the sidewalls of atrench against collapse by initially driving in double-T vertical pilotbeams before the beginning of excavation. As excavation progresses,arrisss timbers are placed between the vertical pilot beams. Since thearriss timbers should not exceed a certain length with a view totransportation and handling, the vertical pilot beams also have to bearranged at correspondingly intervals. In many cases, the arris timbersIn conventional methods of construction, formwork for the foundationshas to be set up at a distance from the system strengthening the wallsof the trench, consisting of vertical pilot beams and arris timbers,after the trench has been excavated. By virtue of the fact that enoughspace for the labourers must be available between the strengtheningsystem for the walls of the trench and the formwork for the building,the trench must be considerably larger than the ground plan of thecompleted building. After the foundations have been laid, this space hasto be refilled so that the excavated material accumulating herefrequently has to be carried away in two shifts. This naturally involvesconsiderable expense, particularly in the case of building works inlarge towns where limited space is available for the building site.

This disadvantages can be obviated by the process according to theinvention. In FIG. 24, the ground around the edge of the trench isdenoted by the refrence B. Double-T vertical pilot beams are driven inaround the edge of the trench at suitable intervals which may beconsiderably larger than in cases where arris timbers are used. Asexcavation progresses, panellike structural units 1 are secured-to theinner flanges of the pilot beams 42. As shown in FIGS. 24 and 25, clamps45 are used for fastening. It is also possible, however, to arrange theplate-like units behind that flange of the pilot beams 42 which facesthe trench.

The panel-like structural units comprise pockets 2a and 2b arranged onebehind the other in straight rows at certain intervals. A corrugation 3is arranged between two parallel rows of pockets 2a and 2b. In theembodiment shown in FIGS. 24 and 25, the rows of pockets and hence thecorrugations, too, extend horizontally.

The pockets form an internal cross-section which tapers inwards fromboth end faces. This cross-sectional form is obtained by arching thepockets in their transverse direction. At the same time, openings Aelongated between two adjacent pockets are formed as seen from thefront, cf. FIG. 26.

By virtue of their special design, the panel-like structural units 1 canbe laid one on top of the other with their edges, as shown in FIG. 24 at21. At the same time, openings into which rod-like connecting elements 8can be inserted are left free in the longitudinal direction of the rowsof pockets.

As the trench progresses, permanent formwork is obtained in this waythrough the units 1 at a distance from the wall adjoining the trench atwhich the ground is exposed.

The space formed in this way is filled in accordance with theprocess ofthe invention by spraying concrete against the'formwork through a spraynozzle 47. If, as provided in accordance with the invention, theconcrete is sprayed at a right-angle to the formwork and the units 1, itpenetrates through the formwork without rebounding in appreciablequantities and fills the space 46 immediately adjacent the ground B. Theconcrete sprayed at a right-angle to the formwork is distributed byvirtue of the fact that the pockets 2b projecting towards the space 46to be filled form convex surfaces to the concrete leaving the nozzle 47.

In this way, the trench is not only protected against collapse duringexcavation, the formwork consisting of cannot be recovered, so that theyremain in the ground,

rot and cause subsidence.

the panel-like units may readily be incorporated in the building 48 tobe erected. Accordingly, there is no need

1. A tunnel structure or the like having a predetermined internal crosssection for permanent installation in a tunnel excavation having aworkface and being driven beneath the ground in a predetermineddirection, said tunnel structure or the like, comprising A. a pluralityof structural panel units arranged in end overlapping manner as apermanent formwork having a cross section definitive of saidpredetermined internal tunnel cross section; B. each of said structuralpanel units including a. a series of parallel, longitudinalcorrugations, the walls of which define crests lying in upper planes andtroughs lying in lower planes, said corrugations being transverse to thedirection of driving of said tunnel; b. a series of bandlike pocketforming elements derived from portions of said crests between pairs oftransverse cuts in said crests at predetermined intervals along saidcorrugations; c. said bandlike pocket forming elements being ofnonuniform width and being depressed from the plane of said crests intoa pocket forming plane bridging said corrugation; d. a series oflongitudinally extending pockets having spaced upper wall portionsdefined by said crests and lower wall portions spaced alternately ofsaid crests defined by said bandlike elements; e. said pocket formingelements being narrowest at the longitudinal centerline of said pocketsand widest at the opposite sides of said pockets; f. said panel, inlongitudinal elevation, thereby having rows of alternating wedge-shapedcrest portions and wedge-shaped pocket forming elements separated bywedge-shaped gaps; g. whereby said panel is readily matable with anotherpanel of identical configuration by nesting therewith, said nestedpanels forming composite longitudinal pockets, the upper walls of whichare defined only by said crest portions of the underlying nested paneland the lower walls of which are defined only by said pocket formingelements of said overlying panel; C. rodlike members extending throughsaid pockets to connect overlapped, nested end portions of saidstructural panel units; D. said permanent formwork being inwardly spacedfrom walls of said excavation and defining a predetermined gaptherebetween; E. a concrete lining tightly filling said gap and pocketsof said panel units, said lining comprising consecutively installedsections formed by introduction of concrete behind said formwork andvibration of said concrete in said gap to bond said lining to the wallsof said excavation and said panel units; F. front formwork meansdisposed in each section of lining of the tunnel structure at the endsof the structural panel units which are forwardmost in sAid direction ofdriving to maintain said ends free of concrete, thereby accommodatingconnection by rodlike members with the rear ends of the structural panelunits of the next section of said formwork and said lining to beinstalled.
 2. A tunnel structure or the like according to claim 1,further characterized in that A. said front formwork means at theforwardmost ends of each section of lining in the direction of drivingis formed by the rearwardmost overlapping ends of said structural panelunits for the formwork of the next installed lining section; B. saidoverlapping panel unit portion being of predetermined length and beingbent toward and against the walls of said tunnel excavation to close offsaid gap in the direction of tunnel driving.
 3. A tunnel structure inaccordance with claim 2, in which A. support wire means connect saidnext installed structural panel units with the structural panel unitsassociated with the formwork for the preceding section of lining.
 4. Atunnel structure or the like for a tunnel having a predeterminedinternal cross section being driven in a predetermined direction througha tunnel excavation having walls and a workface, said tunnel structureor the like, comprising A. a plurality of temporary erection arches,each having said predetermined internal cross section of said tunnel; B.a temporary workface erection arch having a web and inner and outerflanges, said temporary workface erection such arch being locatedimmediately adjacent the workface and having a cross section generallycorresponding to that of the tunnel excavation walls adjacent saidworkface; C. a plurality of overlapping structural panel units supportedby said temporary erection arches and defining a permanent formwork,said permanent formwork and said excavation walls defining a gaptherebetween; D. a concrete tunnel lining disposed in said gap, saidlining comprising consecutively installed sections of concrete; and E. afront formwork means for closing off the permanent formwork proximate tosaid workface and for maintaining the front ends of the forwardmoststructural panel units free of concrete.
 5. The tunnel structure or thelike of claim 4, in which A. said front formwork means comprises abox-shaped projection nested between said flange of said temporaryworkface arch; B. the front wall of said projection closes off the lastsection of lining and includes a roof-like projection whose base portionprojects beyond and over forward ends of the structural panel units; C.said base portion being spaced from the inner flange of the workfaceerection arch a distance not less than the maximum height of saidstructural panel units.